tisdag 14 juli 2009

The Fabric of SpaceTime

The idea that space and time are united into something called spacetime, was put forward by the young patent clerk Albert Einstein in a short article in 1905 later referred to as the special theory of relativity. The special theory was generalized by Einstein after 10 years of thinking with the help of the mathematicians Minkowski and Grossman into the general theory of relativity connecting curvature of a spacetime to mass-energy density, as expressed by Einstein's field equations.

Einstein's thought experiment to mix time and space into space-time, has in 20th century physics been elevated to a religion to which all physicists have to confess, even without understanding. A physicist will have to give the impression to understand that we live in a four-dimensional curved spacetime, usually with reference to an illustration like the one above indicating masses distorting some form of flexible spacetime net. But when asked to explain what this means and why this is so in more detail, the physicist will usually back off and admit to not really be familiar with the details of general relativity. You can test the truth of this statement yourself. Just ask! Both a physicist and yourself!

The unfortunate result is a degeneration of science, where rationality is replaced by mysticism, as expanded in my previous blog. The reader who wants some medication or relief from this disease, is wellcome to browse my knols on Relativity Theory and Quantum Mechanics.

Time is not like another space dimension. Any quality which can measured by a scale in space, like time or mass or frequency, is not itself a dimension in space. Elementary, my dear Watson!

Right?

A few statements about space-time:

Ed Witten: On the other hand, we don't understand the theory too completely, and because of this fuzziness of spacetime, the very concept of spacetime and spacetime dimensions isn't precisely defined.

Hannes Alfven, Nobel Prize in Physics 1970: Many people probably felt relieved when told that the true nature of the world could not be understood except by Einstein and a few other geniuses who were able to think in four dimensions. They had tried to understand science, but now it was evident that science was something to believe in, not something which should be understood.

David Gross: Can we imagine physics with more than one dimension of time? What are the rules of physics without spacetime?

Physics without spacetime? Any clue? Is this trivial model physics with all variables being constant in both space and time? Witten and Gross are supposed to be smarter than all of us, but why do they argue as if the opposite was true?